The present invention relates to a method to determine characteristic features of processes forming radicals.
Forming of radicals occurs in numerous thermal and/or chemical conversions as for instance in the combustion of fossil fuels, such as hard or brown coal, heavy oil, natural gas, in the combustion of sewage sludge, waste or hazardous waste, in the gasification of materials containing carbon and also in other chemical and/or thermal processes.
In order to control methods comprising such processes, characteristic features of the respective process are recorded and then generally evaluated correspondingly, for instance in order to form command variables for a process control, especially in view of NO.sub.x and 2,3,7,8 TCDD and dibenzofuran production. Thereby, the recorded characteristic features can directly and/or indirectly form command variables, i.e. for instance after calculation of a basic number.
Various methods to determine the temperature as a characteristic feature are known. With a method operating with a suction pyrometer for instance, a cooled lance is held in a reaction space through the sight hole of a reactor, and the temperature of the sucked off gas quantity determined. Hereby, only a single local temperature will be determined in spite of the high measuring expenditure, whereby the determination in addition contains faults since inserting the lance itself influences the measuring result. Moreover, this method enables only a subsequent evaluation of the temperature which can be allocated locally in the reaction space only inaccurately, and the lance is exposed to high thermal stresses and wear.
For determination of the temperature of chemical and/or thermal processes, contactless methods are also known. It has been proposed to arrange a multitude of acoustic source detector units in a plane outside of the wall surrounding the combustion chamber for contactless determination of the temperature in the combustion chamber of a coal-fired power plant. In this method a source detector unit transmits a short-time acoustic signal such as a bang which is received by the other source detector units. Transmitting and receiving acoustic signals are then exchanged cyclically until each unit has transmitted once and the other units have received correspondingly often. The momentary density of combustion gases and then the temperature of which are concluded from the varying speeds of the sound conveyance through the combustion chamber. This method has the disadvantage that only mean temperature values can be determined since sound waves excited by the source detector units pass only partially through the whole combustion chamber in which, however, the temperature is distributed heterogeneously and not homogeneously, resulting in zones having varying densities of combustion gases. Additionally, dust and skin formations interfere with exact temperature determination.
The determination of radicals generated in combustion processes to control waste combustion processes is also known according to EP-A-0 317 731.
In view of measuring methods inside the combustion chamber of e.g. waste combustion plants, which have been unsatisfactory up to now, exact analyses of the function leading to contaminant formation are still not available.
Especially the detection of local conditions in the conversions previously mentioned is not satisfactorily possible.